Conventional home appliances with telescopic racks typically rely upon ladder type frames, which are attached to side walls of a cavity to support racks for the placement of food and cookware items. The racks may be telescopic, allowing the racks to be extended, at least partially, out of the cavity. These telescopic racks generally have a “slide” type mechanism on opposing sides of the rack with a linear bearing that is attached to the ladder type frame on one side and to the rack on the other, the rack extends horizontally across the interior of the cavity to another linear slide mechanism on an opposite side, which, in turn, is attached to another ladder type frame attached to the opposing side of the cavity. These home appliances are expensive because of the added cost and complexity of providing a ladder frame attached to the cavity wall. Manufacturing costs are increased because of the increase in assembly costs of the ladder frame into the oven cavity and also the cost of the ladder frame on its own.
Another type of home appliance has a cavity that includes racks that do not require a ladder type frame. This type of appliance relies upon the interior wall surface of the cavity to have ribs that directly support a rack in the cavity. There are a number of advantages of a ribbed cavity. A ribbed cavity has improved cavity strength, increased cavity volume, and no additional rack support parts (ladder frame attachments) are required. Therefore, in a ribbed cavity, usable cavity volume is increased, the overall cavity strength is improved, there are less parts (no additional cost for a ladder frame), and there is less variation in parts. Therefore, overall quality and usability of the appliance is improved. However, racks typically used in ribbed cavities do not conventionally include slide rails with linear bearings for ease of extending and retracting the oven rack. Rather, these racks typically rest directly on the ribs and may extend only partially from the cavity by directly sliding upon the ribs in the side walls of the oven.
A number of home appliances having telescopic racks have been developed to be used with the various types of cavities, e.g., ribbed and non-ribbed.
U.S. Pat. No. 4,651,713 discloses a home appliance with a slide out rack that rest directly on the ribs and may partially extend from the cavity by directly sliding upon the ribs in the side wall of the cavity.
U.S. Pat. No. 6,148,813 discloses a home appliance with a rack assembly with a rack frame having rollers and roller guides to facilitate extending a rack.
U.S. Pat. No. 6,938,617 discloses a home appliance with a rack having a rack frame resting on ledges of an interior of the cavity. The rack is coupled to extension slides which are coupled to opposing margins of the rack, and the slides enable the extension of the rack from a position within the cavity to a position outside the cavity.
U.S. Pat. No. 7,087,862 discloses a home appliance with a rack assembly including a pair of laterally spaced inner rails, wherein each inner rail includes a coating layer that survives a high temperature self-clean, and a pair of laterally spaced outer rails. Each outer rail is slidably coupled to a corresponding inner rail, and each outer rail includes a coating layer that survives a high temperature self-clean. The rack assembly also includes a plurality of bearings positioned between the inner rails and the outer rails, a lubricant to facilitate movement between the plurality of bearings, the inner rails and the outer rails. The lubricant of this home appliance maintains its lubricating properties even after being exposed to a high temperature self clean cycle.
The above described home appliances have various disadvantages. For example, none of the conventional home appliances provide a reliable mechanism that secures a rack assembly to ribs on the interior wall surface of the cavity in a manner that prevents the rack from being inadvertently becoming completely disconnected from the cavity when, for example, extending the rack out of the cavity, nor do they provide a reliable mechanism to keep the rack from tilting when the rack is extended out of the cavity, especially while the rack supports a cooking vessel.
The above described conventional home appliances also do not provide a reliable mechanism that prevents the rack from hitting a back wall of the cavity when the rack is fully retracted into the cavity. Further, a number of the conventional home appliances include racks that rest directly on the ribs, without any type of bearing/slide assembly, thus making it difficult to extend and retract the rack. Further still, conventional home appliances fail to provide a reliable chassis design for a telescopic rack that facilitates maintaining the structural integrity of the telescopic rack, preventing the telescopic rack from warping, bending in, and/or skewing during use or over time, which may cause the telescopic rack to become unintentionally disengaged from the support ribs in the cavity.